Embodiments of the disclosure relate to the field of semiconductor device fabrication. More particularly, embodiments of the disclosure provide a method and system for depositing metal layers.
In the manufacturing process of integrated circuits, due to its good gap filling properties, the chemical vapor deposition process is used for depositing a tungsten material, e.g., filling a contact plug, a metal gate electrode, and the like.
As device feature sizes decrease, in order to obtain improved gap filling properties, for example, in order to reduce or eliminate smaller gaps or voids in the filling materials, a deposition-etch-deposition process is generally used.
However, the present inventor discovered that the thickness of the deposited tungsten material is uniform and the thickness fluctuation from wafer to wafer is small in a deposition process. However, the thickness of the tungsten material is uneven and the thickness fluctuation range is large across the processed wafers in a deposition-etch-deposition process. For example, the deposited tungsten material has a thickness of about 3,000 Angstroms and a fluctuation range is about ±100 Angstroms among processed wafers using a deposition process. However, the fluctuation range of the tungsten layer having the same thickness is about ±300 Angstroms among wafers in a deposition-etch-deposition process.
Thus, there is a need for a novel method and system for manufacturing a tungsten layer having a more uniform thickness among multiple wafers while maintaining good gap filling properties.